Full disclosure: I am not a religious nor faith-centered person. Yet it is totally perplexing to me that rational people would actually think, nevermind say, that Catholics, or any other religious person, should not impose their beliefs on the rest of us. I suppose the basic principle, if there is one, that is being argued is that of the often misused “separation of church and state”?
Generally speaking, who cares how you have come to believe what you do? In an argument about beliefs and principles we can discuss the merits without worrying about the basis for them. It may be useful in an evaluation of your principles and credibility to understand how you came to believe what you do, but otherwise the source is irrelevant to the rightness or wrongness of the issue being discussed.
If you believe that abortion is murder it doesn’t matter if it is because you are simply accepting the teachings of your church or because you are a philosopher who believes the unborn have moral status. I cannot figure out why people don’t get this – unless they are simply disingenuous and looking for any counter-argument that might work.